lecture four dental pulp.pptx Oral histology

Important for dental students

1. Dr . Ahmed mohamed BDS

2. I n t r o D u c t I o n The Pulp is a soft mesenchymal connective tissue that O c c up i e s pu lp cav i t y in t h e c e n t r a l par t of t he teeth. I t is a s p e c ial org a n be c a us e o f t h e u n i q u e environment

3. Features oF pulp Surrounded by rigid walls (dentin) - unable to expand in response to injury as a part of the inflammatory process Therefore pulpal tissue is susceptible to change in pressure affecting the pain threshold Pulp is simple connective tissue Peripherally layer of specialized cells (odontoblasts) Secondary dentin deposited gradually (physiological process) reduces the blood supply Making the tooth resistant to trauma or infection

4. coronal pulp • • • • • Pulp occupying the pulp chamber of the crown of the tooth In young teeth it resembles the shape of the outer dentin It has six surfaces : occlusal, mesial, distal, buccal, lingual and floor. Pulp horns are projections into the cusp T his pu lp c on s t ri c t s at the ce r v i c a l r egi o n w h ere it continues as the radicular pulp

5. raDIcular pulp Pulp occupying the pulp canals of the root of the tooth I n th e an t e r ior t o o t h it is s i ng le a n d in t he posterior teeth it is multiple T h e r a d i c u l a r p o r t i o n s of t h e p u lp is con ti n u ous with the periapical tissues through apical foramen As age advances the width of the radicular pulp is reduced , and so is the apical foramen .

6. apIcal ForaMen Pu lp c a vi t y t e r mi na t e s at ro o t a p e x as s m all opening called apical foramen Radicular pulp continuous with connective tissue of the periodontium through this foramen. D ia m e t e r in a n a d u l t - m a x illary tee t h - 0.4 m m mandibular teeth-0.3mm Wide open during development of root

7. apIcal ForaMen So m e ti me s a p i c a l o pe n i n g is f ound on th e la t e ral side of the apex There may be 2-3 foramina split by cementum or dentin- APICAL DELTA Neurovascular bundle entering pulp through the foramen

8. accessory canals Leading laterally from the radicular pulp into the periodontal tissue. They are numerous in the apical third of the root. Formed due to premature loss of HERS or when developing root encounters a blood vessel. Overall occurrence is 33% May also be present at the furcation region

9. structural organIzatIon oF pulp

10. hIstologIcal zones oF pulp • Odontoblast layer • Cell-free zone • Cell-rich zone • Pulp proper

11. Dentin Predentin Odontoblasts layer Cell free zone Cell rich zone Pulp core

12. oDontoBlastIc layer  Location: Adjacent to the predentin with the cell bodies in the pulp and cell processes in the dentinal tubules. Dentin

13. cell Free zone It is also called weil’s zone 40 microns wide &relatively free of cells Traversed by 1. Blood vessels 2. Unmyelinated nerves 3. Cytoplasmic process of fibroblasts This zone is found below the odontoblastic zone

14. c e l l r I c h z o n e Present in subodontoblastic layer • • • • • • C o nt a i ns m o r e p r o p o r t io n s of f i b r o b l a s t a nd undifferentiated mesenchymol cells. Macrophages, dendritic cells and lymophocytes. Z o ne f o r m e d due t o m i g rat i o n o f cell s f r o m pu lp proper Mitosis seen when dead odontoblasts are replaced Als o c o nt a i n y o u n g coll ag e n f i b r es du ri ng ea rly dentiogenis.

15. pulp core It is central region of the pulp C o nt a i n s ma j o r b l o od v e s s e ls and n e r v e s o f t he pulp Pulpal cells and fibroblasts are also seen

16. CELLS OF PULP Odontoblasts Fibroblasts Undifferentiated Cells Defense Cells

17. ODONTOBLASTS A P e r i phe r a l a r e a o f th e pu lp w her e t he odontoblasts reside is termed odontogenic zone. A rrange d in P a l i sad i n g pa tt e r n c e lls are t all columnar forming a layer of 3 to 5 cells in depth. Shape may vary Cornal pulp- columnar Midportion - cuboidal Apical region - Flattened

18. ODONTOBLASTS T hes e c e lls h a ve lar g e p r o c es s ex t e nd i n g i n t o dentin The re is no of odontoblasts corresponds to the number of dentinal tubules A v e r a g e n o o f od o n to b l a s t s es ti m a t e d t o 4 5 , per Sq.mm of odontogenic zone. O don to b l a s t s in t h e c r o w n are l a r g e r t ha n in t he root .

19. ODONTOBLASTS Shap e of th e od o n t obl a s t s al s o r e f l e c t t he functional activity of the cell . During active ph a s e , c e lls sh o w i n c r e a s e in e n d oplas m ic r e t i c u l u m gol g i app a r t u s and secretory vesicles. Resting (or) Non active phase cells are flattened little cytoplasm condensed chromatin and decrease no of ER

20. ODONTOGENiC PROCESS Odontoblasts give off a single process that extends into dentin and housed within dentinal tubules These process devoid of major organelles T he y con tain a b u n d a nc e o f m i c r o tubu l a r filaments and coated vesicles

21. F i B R O B A L S T S Cells that occur in greatest number in the pulp Function is to form, maintain the matrix that consists of collagen fibers and ground substance throughout the pulp They are spindle in shape. The fibroblasts are stellate shaped cells having extensive process.

22.  T h e nuc l e u s s t ai n s d ee p w i t h b a s ic d y e and the cytoplasm is highly stained and homogenous . H&E stain I m m u no h istoc hemical method

23.  These cells have a dual function : synthesize and degradation of fibers and ground substances in the same cell . In young pulp: large cells with large multiple processes centrally located oval nucleus , numerous mitochondria , well developed golgi bodies well developed RER Fibroblast (protein secreting cell).

24.  In periods of less activity and aging these cells appear smaller and round or spindle-shaped with few organelles , they are termed fibrocytes.

25. UNDiFFERENTiATED mESENCHYmE • • These mesenchymal cells are distributed through out the pulp , frequently around the perivascular area - believed to be toti potent cell They are Polyhedral shaped with peripheral processes and large oval nuclei • • • Di ff ic u l t t o d i f fe re nt i a t e f r o m f i brob l a s t under li g ht microscopy U n d e r a d e q u a t e s t i m il u s t h e y m a y d i f f er en t i a t e i nto odontoblast or fibroblast or macrophages . I n ol d e r p u l p , th ei r n umb e r a n d a b ili t y t o d i f f ere n t i a t e comes down

26. DEFENCE CELLS T he y p lay a m a j or ro le local i n f la mma t i o n and immunity . They are recruited from blood stream and remain as transient inhabitants in pulp These cells are Macrophages Mast cells Plasma cells Lympocytes, Neutrophils, Eosinophils, basophils and manocytes.

27. Structure of Tooth A - crown B - enamel C - dentine D - gum E - tooth pulp F - cement H - nerves & blood vessels

28. Clinically Importance features of the Dental Pulp  With age the pulp becomes less cellular . The number of cells in the dental pulp decreases as cell death occurs with age.  The volume of the pulp chamber decreases with continued deposition of secondary dentine. In older teeth, the pulp chamber decreases in size ; in some cases the pulp chamber can be obliterated .  An increase in calcification in the pulp occurs with age.

29. Age ch an es in the p lp Age chan g ges in the p u ulp The size of the pulp The apical foramen The cellular elements The bl. vessels & n. Vitality d e cr ea s ed

30. Pulp calcification localized ( pulp stones ) d i f f u s e False denticle True denticle

31. Functions of the pulp Functions of the pulp Inductive: Dental papilla induces the enamel organ formation and also determines the morphology of the tooth . Formative : Pulp organ produces dentin. Odontoblasts develop the organic matrix and function in its calcification.

32. Reparative: through the formation of highly mineralized reparative dentin at the site of injury to seal off the pulp from the source of irritation . Also the pulp may mineralize the affected dentinal tubules by forming sclerotic dentin . Defensive : pulp inflammation represents other aspect of its response to irritation. In this condition, the defensive cells of the pulp will be increased and activated to repair and heal the inflamed pulp and phagocytoses the invading bacteria and their toxin .

33. Protective: : any environmental irritating stimuli always elicit pain as a response . Nutritive : the extensive pulp vasculature ensures an excellent nourishment to the odontoblasts for the continuously forming secondary dentin . This is provided through the capillaries found in the odontogenic zone .